Method for Improved Handling of IP Multimedia Subsystem Calls in a Home Mobile Communication Network and a Visited Mobile Communication Network

1. A method for handling of IP multimedia subsystem calls and configuration of a user equipment, wherein the method comprises: roaming, by the user equipment, to a visited mobile communication network, wherein the user equipment comprises previously stored IP multimedia subsystem call-related parameters from a home mobile communication network; receiving, by the user equipment, IP multimedia subsystem call parameter information from the visited mobile communication network, wherein the user equipment is connected to the visited mobile communication network via a radio access network associated with the visited mobile communication network, wherein the IP multimedia subsystem call parameter information comprises parameter information that is adjusted to the visited mobile communication network, and wherein the visited mobile communication network modifies the previously stored IP multimedia subsystem call-related parameters from the home mobile communication network via the IP multimedia subsystem call parameter information; and attempting, by the user equipment, to connect to an IP multimedia subsystem locally via the visited mobile communication network and to place an IP multimedia subsystem call, wherein upon attempting to connect to the IP multimedia subsystem and to place the IP multimedia subsystem call, the user equipment utilizes the content of the IP multimedia subsystem call parameter information rather than utilizing the previously stored IP multimedia subsystem call-related parameters; wherein the visited mobile communication network modifies one or more GSMA PRD IR.92 Table C.3.1 parameters of the user equipment; wherein the previously stored IP multimedia subsystem call-related parameters comprises previously stored IP multimedia subsystem emergency call-related parameters; wherein the IP multimedia subsystem call parameter information comprises IP multimedia subsystem emergency call parameter information; and wherein the IP multimedia subsystem call is an IP multimedia subsystem emergency call.

2. The method according to claim 1, wherein the user equipment utilizes the content of the IP multimedia subsystem call parameter information for performing IP multimedia subsystem emergency call procedures, including an emergency attach procedure, an IP multimedia subsystem emergency registration procedure, and/or an IP multimedia subsystem emergency call procedure.

3. The method according to claim 1, wherein the user equipment utilizes the content of the IP multimedia subsystem call parameter information for performing IP multimedia subsystem call procedures, including an access network attach procedure and/or an IP multimedia subsystem registration procedure.

4. The method according to claim 1, wherein the previously stored IP multimedia subsystem call-related parameters are related to multiple visited mobile communication networks.

5. The method according to claim 1, wherein the IP multimedia subsystem call parameter information relates either to different management objects or to only one management object.

6. The method according to claim 1, wherein the IP multimedia subsystem call parameter information is transmitted to the user equipment via at least one out of the following transport protocols: rich communication services (RCS); open mobile alliance device management (OMA DM); an extended LTE attach procedure; an extended emergency registration procedure; and/or a dedicated protocol specifically used for transmitting the IP multimedia subsystem call parameter information.

7. The method according to claim 1, wherein the user equipment utilizes the content of the IP multimedia subsystem call parameter information during a certain validity time interval.

8. The method according to claim 1, wherein the visited mobile communication network alters an IP multimedia subsystem call parameter of the user equipment regarding whether or not anonymous emergency calls are allowed.

9. The method according to claim 1, wherein the visited mobile communication network modifies one or more of the following IP multimedia subsystem call parameters of the user equipment: a parameter indicating whether use of the IP multimedia subsystem is enabled; a parameter indicating whether voice over LTE and/or video over LTE is allowed; a parameter indicating when to use SMS over IP; a parameter indicating a base wait time after an attempt to register with the IP multimedia system has failed; a parameter indicating a maximum wait time after an attempt to register with the IP multimedia system has failed; a parameter indicating a policy on local numbers; a parameter indicating an SIP timer T1; a parameter indicating an SIP timer T2; a parameter indicating an SIP timer T4; a parameter indicating whether an SIP 18× response is to be sent reliably; a parameter indicating an operator's originating party identity determination policy; a parameter indicating whether use of a precondition mechanism is allowed; a parameter indicating a default EPS bearer context usage restriction policy; a parameter indicating bit rates used by an AMR codec; a parameter indicating bit rates used by an AMR-WB codec; a parameter indicating bit rates used by an EVS codec; a parameter indicating an initial partial redundancy offset; a parameter indicating a policy on a PDN connection established during an EPS attach procedure; a parameter indicating whether MMTEL voice is a 3GPP PS data off exempt service; a parameter indicating whether to use SMS over IP; a parameter indicating whether device management over PS is a 3GPP PS data off exempt service; or a parameter indicating whether USSI is a 3GPP PS data off exempt service.

10. The method according to claim 1, wherein the user equipment attempts to connect to an IP multimedia subsystem locally via the visited mobile communication network using local breakout.

11. A system for handling of IP multimedia subsystem calls and configuration of a user equipment, wherein the system comprises: the user equipment; and the visited mobile communication network; wherein user equipment is configured to roam to the visited mobile communication network, wherein the user equipment comprises previously stored IP multimedia subsystem call-related parameters from a home mobile communication network; wherein the visited mobile communication network is configured to transmit IP multimedia subsystem call parameter information to the user equipment, wherein the user equipment is connected to the visited mobile communication network via a radio access network associated with the visited mobile communication network, wherein the IP multimedia subsystem call parameter information comprises parameter information that is adjusted to the visited mobile communication network, and wherein the visited mobile communication network modifies the previously stored IP multimedia subsystem call-related parameters from the home mobile communication network via the IP multimedia subsystem call parameter information; and wherein the user equipment is configured to attempt to connect to an IP multimedia subsystem locally via the visited mobile communication network and to place an IP multimedia subsystem call, and upon attempting to connect to the IP multimedia subsystem and to place the IP multimedia subsystem call, utilize the content of the IP multimedia subsystem call parameter information rather than applying or acting according to the previously stored IP multimedia subsystem call-related parameters; wherein the visited mobile communication network modifies one or more GSMA PRD IR.92 Table C.3.1 parameters of the user equipment; wherein the previously stored IP multimedia subsystem call-related parameters comprises previously stored IP multimedia subsystem emergency call-related parameters; wherein the IP multimedia subsystem call parameter information comprises IP multimedia subsystem emergency call parameter information; and wherein the IP multimedia subsystem call is an IP multimedia subsystem emergency call.

12. A user equipment for handling of IP multimedia subsystem calls and configuration of the user equipment, comprising a processor and a memory having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by the processor, facilitate performance of the following by the user equipment: roaming, by the user equipment, to a visited mobile communication network, wherein the user equipment comprises previously stored IP multimedia subsystem call-related parameters from a home mobile communication network; receiving, by the user equipment, IP multimedia subsystem call parameter information from the visited mobile communication network, wherein the user equipment is connected to the visited mobile communication network via a radio access network associated with the visited mobile communication network, wherein the IP multimedia subsystem call parameter information comprises parameter information that is adjusted to the visited mobile communication network, and wherein the visited mobile communication network modifies the previously stored IP multimedia subsystem call-related parameters from the home mobile communication network via the IP multimedia subsystem call parameter information; and attempting, by the user equipment, to connect to an IP multimedia subsystem locally via the visited mobile communication network and to place an IP multimedia subsystem call, wherein upon attempting to connect to the IP multimedia subsystem and to place the IP multimedia subsystem call, the user equipment utilizes the content of the IP multimedia subsystem call parameter information rather than utilizing the previously stored IP multimedia subsystem call-related parameters; wherein the visited mobile communication network modifies one or more GSMA PRD IR.92 Table C.3.1 parameters of the user equipment; wherein the previously stored IP multimedia subsystem call-related parameters comprises previously stored IP multimedia subsystem emergency call-related parameters; wherein the IP multimedia subsystem call parameter information comprises IP multimedia subsystem emergency call parameter information; and wherein the IP multimedia subsystem call is an IP multimedia subsystem emergency call.

13. A non-transitory computer-readable medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed, facilitate performance of the following: roaming, by a user equipment, to a visited mobile communication network, wherein the user equipment comprises previously stored IP multimedia subsystem call-related parameters from a home mobile communication network; receiving, by the user equipment, IP multimedia subsystem call parameter information from the visited mobile communication network, wherein the user equipment is connected to the visited mobile communication network via a radio access network associated with the visited mobile communication network, wherein the IP multimedia subsystem call parameter information comprises parameter information that is adjusted to the visited mobile communication network, and wherein the visited mobile communication network modifies the previously stored IP multimedia subsystem call-related parameters from the home mobile communication network via the IP multimedia subsystem call parameter information; and attempting, by the user equipment, to connect to an IP multimedia subsystem locally via the visited mobile communication network and to place an IP multimedia subsystem call, wherein upon attempting to connect to the IP multimedia subsystem and to place the IP multimedia subsystem call, the user equipment utilizes the content of the IP multimedia subsystem call parameter information rather than applying or acting according to the previously stored IP multimedia subsystem call-related parameters; wherein the visited mobile communication network modifies one or more GSMA PRD IR.92 Table C.3.1 parameters of the user equipment; wherein the previously stored IP multimedia subsystem call-related parameters comprises previously stored IP multimedia subsystem emergency call-related parameters; wherein the IP multimedia subsystem call parameter information comprises IP multimedia subsystem emergency call parameter information; and wherein the IP multimedia subsystem call is an IP multimedia subsystem emergency call.